It is well known that Poncirus trifoliata harmonizes the Stomach dissipates the Nodules of Liver and manages Vitality. This herb has been used for stomachache, vomitting, nausea, abdominal distension and swelling of testis in the Oriental Medicine. A major components of Poncirus trifoliata consist of a various flavonoids such as poncirin, naringin, hesperidin, neohesperidin, rhoifolin, poncimarin, poncitrin. Generally pharmacological activities of an oriental medicinal drug may be different due to diverse origin, harvest season and storage Period. In this study, we aimed to measure the contents of poncirin and naringin, major flavonoid of this herb, to determine the quality of Poncirus trifoliata.